Facts not ‘flexible’ in dating earliest Americans

Determining when humans discovered America is one of the most fascinating and contentious problems in archaeology.

An article in the September/October issue of Archaeology reviews the oldest well-documented sites in the so-called New World. One of them is next door in western Pennsylvania.

Meadowcroft Rockshelter, located less than 10 miles southeast of Steubenville, is described by excavator James Adovasio of Mercyhurst University as “a late-Pleistocene Holiday Inn” — a place where early Americans camped for short periods.

Meadowcroft Eastern Profile

Adovasio and his team have excavated 50 tools and 700 pieces of chipped stone, including some made from Ohio’s Flint Ridge flint, dating to about 15,000 years ago.

There have been several claims for sites even older than those considered in the Archaeology review.

It’s fun to contemplate an extreme antiquity for the peopling of America, but the history of the modern human migration out of Africa and the genetics of modern American Indians suggest that people did not enter this hemisphere much before 16,000 years ago.

Claims for older sites shouldn’t be dismissed, but they must be carefully evaluated.

In the current issue of the journal Antiquity, an international team of archaeologists working in South America argues that they have found evidence of people who had lived in eastern Brazil more than 20,000 years ago. The site of Vale da Pedra Furada is located at the base of a cliff where rocky debris has accumulated for thousands of years.

Although flint was locally available and used by later cultures at the site, all of the artifacts in the deepest layers are made from quartz.

Quartz cobbles occur naturally in the area, and some archaeologists have expressed the opinion that the so-called artifacts formed when quartz cobbles tumbled down the cliff, becoming broken and battered. A few might have ended up resembling tools.

The excavators believe they are able to tell the difference between natural breakage and the results of human manufacture. In spite of their confidence, many archaeologists aren’t convinced. If there were people there 20,000 years ago, why didn’t they use the nearby flint?

In a commentary on the article, Vanderbilt University archaeologist Tom Dillehay raises questions about the evidence.

He concedes that “the earliest human record in South America is more diverse and, in several ways, different from that in North America and should be viewed with more flexible standards and expectations.” But he said that some aspects of the research “need more detailed reporting.”

For example, what criteria did the excavators use to differentiate between naturally broken bits of quartz and those identified as artifacts? If they really are artifacts, do they occur together in activity areas? Can some of the quartz chips be refitted to the tools, which would show the tools were made on the spot?

I am open to the possibility of finding evidence for people in the Americas before 16,000 years ago, but I disagree with Dillehay.

It’s fine for the evidence to defy our expectations, but it must be held to the highest standards before we rewrite the opening chapter of America’s story.